Replace Mock Database With Real Postgres Database For Integration / Unit Testing

[elraphty]

Context

Currently, we use Mock Database for our Business Logic tests using github.com/stretchr/testify/mock, the issue with using the mock DB is the Mock will always return a response if the right input is provided, and cannot assert that the SQL query is working as it should.

e.g

func TestBountyMetrics(t *testing.T) {
	ctx := context.WithValue(context.Background(), auth.ContextKey, "test-key")
        // Mock DB
	mockDb := mocks.NewDatabase(t)
	mh := NewMetricHandler(mockDb)

	t.Run("should fetch bounties count within specified date range", func(t *testing.T) {
		db.RedisError = errors.New("redis not initialized")
		rr := httptest.NewRecorder()
		handler := http.HandlerFunc(mh.MetricsBountiesCount)
		dateRange := db.PaymentDateRange{
			StartDate: "1111",
			EndDate:   "2222",
		}
		body, _ := json.Marshal(dateRange)
		req, err := http.NewRequestWithContext(ctx, http.MethodPost, "/boutnies/count", bytes.NewReader(body))
		if err != nil {
			t.Fatal(err)
		}

                // Using mock DB function
		mockDb.On("GetBountiesByDateRangeCount", dateRange, req).Return(int64(100)).Once()
		handler.ServeHTTP(rr, req)

		var res int64
		_ = json.Unmarshal(rr.Body.Bytes(), &res)

		assert.Equal(t, http.StatusOK, rr.Code)
		assert.Equal(t, res, int64(100))
	})
}

Design

We want to create a Postgres database and then test the database functions to assert that the SQL queries work as they should.

We can achieve this using these two approaches

1. Create a database programmatically, and drop the database after all the tests are processed.
2. Using Docker Compose to spin up a Postgres container, the tests will connect to the Postgres DB, and then after the test, we will drop the Postgres container

Programmatic Postgres Database Creation

Pros

• It's easier to run on Local, running the go test command go test ./.... spins up the database before running the test.

Cons

• Uncertainty on how long it will take for the Postgres DB to spin up for now, which may lead to test timing out.
• Requires more experience and understanding of the library to maintain the code for future purposes

Docker Compose Database Creation

Pros

• The Database will be up and running before the Go tests start, which will reduce the likelihood of tests failing due to DB connection timeout
• Easier to pick up and edit In the future buy anyone who understands docker and docker-compose

Cons

• One has to run the docker-compose-up command before running the Golang, and docker-compose-down after the Golang test, running this process on GitHub actions will make the commands easier since it's a constant.

REFERENCES

• https://github.com/ory/dockertest
• https://medium.com/@suuum/testing-in-golang-part-2-database-integration-tests-ad6880de22b4
• https://semaphoreci.com/community/tutorials/building-and-testing-a-rest-api-in-go-with-gorilla-mux-and-postgresql

Acceptance Criteria

• I've tested on Chrome
• I've created a test that...
• I have rebased and tested locally before submitting my PR
• I can submit a PR within 4 days of taking the bounty

Here is an example backend test